In recent years, many proposals of a member excellent in absorptivity of shock energy or the like which comprises a ceramic as a main constituent material have been made. In Patent Literature 1, for example, a protective member in which a shock receiving part comprising a ceramic containing boron carbide as a main component and a basic part comprising a ceramic containing silicon nitride as a main component are bonded by a bonding layer comprising a resin is described. Moreover, in Patent Literature 2, a shock absorbing member in which a sheet made from partially stabilized zirconia and a sheet made from boron carbide, mullite, or the like are laminated and bonded with an epoxy resin or the like is described.
On the other hand, it is known that not only a shock absorbing member but also a highly functional structural material can be obtained by laminating members comprising a ceramic or the like. In Patent Literature 3, for example, a laminated sintered body useful as a cutting tool strong against thermal shock which comprises a base material comprising: a ceramic or a sintered alloy; an intermediate layer comprising a ceramic; and an outermost layer comprising a ceramic and having a thermal expansion coefficient smaller than that of the base material is described. In addition, it is described that alumina, silicon nitride, boron nitride, silicon carbide, and so on are appropriately combined to be used as a ceramic that constitutes the base material or the outermost layer.
Moreover, in Patent Literature 4, a laminated structured sintered body that is useful for a cutting tool to be used under severe conditions and comprises a metal; a ceramic such as alumina or the like; and cermet is described. Furthermore, in Patent Literature 5, a silicon nitride sintered body with a laminated structure obtained by laminating a layer of porous silicon nitride and a layer of dense silicon carbide, the silicon nitride sintered body having a strong tolerance against shock, stress, or distortion is described.